Varied spin crossover behaviour in a family of dinuclear Fe(ii) triple helicate complexes

2018 ◽  
Vol 47 (24) ◽  
pp. 7965-7974 ◽  
Author(s):  
Rosanna J. Archer ◽  
Hayley S. Scott ◽  
Matthew I. J. Polson ◽  
Bryce E. Williamson ◽  
Corine Mathonière ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Variable Temperature ◽  
Triple Helicate

A family of dinuclear Fe(ii) triple helicate complexes has been structurally characterised and their spin crossover behaviour studied using a variety of variable temperature physical techniques.

scholarly journals Solvent Effects on the Spin-Transition in a Series of Fe(II) Dinuclear Triple Helicate Compounds

Crystals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 376 ◽  
Author(s):  
Alexander Craze ◽  
Mohan Bhadbhade ◽  
Cameron Kepert ◽  
Leonard Lindoy ◽  
Christopher Marjo ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Condensation Product ◽  
Variable Temperature ◽  
Spin Transition ◽  
Single Step ◽  
Spin Conversion ◽  
Dinuclear Iron ◽  
Solvent Molecules ◽  
State Spin ◽  
Triple Helicate

This work explores the effect of lattice solvent on the observed solid-state spin-transition of a previously reported dinuclear Fe(II) triple helicate series 1–3 of the general form [FeII2L3](BF4)4(CH3CN)n, where L is the Schiff base condensation product of imidazole-4-carbaldehyde with 4,4-diaminodiphenylmethane (L1), 4,4′-diaminodiphenyl sulfide (L2) and 4,4′-diaminodiphenyl ether (L3) respectively, and 1 is the complex when L = L1, 2 when L = L2 and 3 when L = L3 (Craze, A.R.; Sciortino, N.F.; Bhadbhade, M.M.; Kepert, C.J.; Marjo, C.E.; Li, F. Investigation of the Spin Crossover Properties of Three Dinuclear Fe(II) Triple Helicates by Variation of the Steric Nature of the Ligand Type. Inorganics. 2017, 5 (4), 62). Desolvation of 1 and 2 during measurement resulted not only in a decrease in T1/2 and completeness of spin-crossover (SCO) but also a change in the number of steps in the spin-profile. Compounds 1 and 2 were observed to change from a two-step 70% complete transition when fully solvated, to a single-step half complete transition upon desolvation. The average T1/2 value of the two-steps in the solvated materials was equivalent to the single T1/2 of the desolvated sample. Upon solvent loss, the magnetic profile of 3 experienced a transformation from a gradual SCO or weak antiferromagnetic interaction to a single half-complete spin-transition. Variable temperature single-crystal structures are presented and the effects of solvent molecules are also explored crystallographically and via a Hirshfeld surface analysis. The spin-transition profiles of 1–3 may provide further insight into previous discrepancies in dinuclear triple helicate SCO research reported by the laboratories of Hannon and Gütlich on analogous systems (Tuna, F.; Lees, M. R.; Clarkson, G. J.; Hannon, M. J. Readily Prepared Metallo-Supramolecular Triple Helicates Designed to Exhibit Spin-Crossover Behaviour. Chem. Eur. J. 2004, 10, 5737–5750 and Garcia, Y.; Grunert, C. M.; Reiman, S.; van Campenhoudt, O.; Gütlich, P. The Two-Step Spin Conversion in a Supramolecular Triple Helicate Dinuclear Iron(II) Complex Studied by Mössbauer Spectroscopy. Eur. J. Inorg. Chem. 2006, 3333–3339).

Supramolecular Modulation of Spin Crossover in an Fe(II) Dinuclear Triple Helicate

2021 ◽  
Author(s):  
Alexander R. Craze ◽  
Hikaru Zenno ◽  
Michael C. Pfrunder ◽  
John C. McMurtrie ◽  
Shinya Hayami ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Triple Helicate

scholarly journals Spin State Behavior of A Spin-Crossover Iron(II) Complex with N,N′-Disubstituted 2,6-bis(pyrazol-3-yl)pyridine: A Combined Study by X-ray Diffraction and NMR Spectroscopy

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 793
Author(s):  
Elizaveta K. Melnikova ◽  
Dmitry Yu. Aleshin ◽  
Igor A. Nikovskiy ◽  
Gleb L. Denisov ◽  
Yulia V. Nelyubina
Keyword(s):  
Nmr Spectroscopy ◽  
Spin State ◽  
Metal Ion ◽  
Spin Crossover ◽  
Molecular Design ◽  
Chemical Shifts ◽  
Variable Temperature ◽  
High Spin State ◽  
X Ray Diffraction ◽  
X Ray

A series of three different solvatomorphs of a new iron(II) complex with N,N′-disubstituted 2,6-bis(pyrazol-3-yl)pyridine, including those with the same lattice solvent, has been identified by X-ray diffraction under the same crystallization conditions with the metal ion trapped in the different spin states. A thermally induced switching between them, however, occurs in a solution, as unambiguously confirmed by the Evans technique and an analysis of paramagnetic chemical shifts, both based on variable-temperature NMR spectroscopy. The observed stabilization of the high-spin state by an electron-donating substituent contributes to the controversial results for the iron(II) complexes of 2,6-bis(pyrazol-3-yl)pyridines, preventing ‘molecular’ design of their spin-crossover activity; the synthesized complex being only the fourth of the spin-crossover (SCO)-active kind with an N,N′-disubstituted ligand.

scholarly journals Solution-State Spin Crossover in a Family of [Fe(L)2(CH3CN)2](BF4)2 Complexes

2019 ◽  
Vol 5 (2) ◽  
pp. 22
Author(s):  
Benjamin Wilson ◽  
Hayley Scott ◽  
Rosanna Archer ◽  
Corine Mathonière ◽  
Rodolphe Clérac ◽  
...  
Keyword(s):  
Thermodynamic Parameters ◽  
General Formula ◽  
Spin Crossover ◽  
Variable Temperature ◽  
Spectroscopic Studies ◽  
Solution State ◽  
Uv Visible ◽  
State Spin

We report herein on five new Fe(II) complexes of general formula [Fe(L)2(NCCH3)2](BF4)2•xCH3CN (L = substituted 2-pyridylimine-based ligands). The influence of proximally located electron withdrawing groups (e.g., NO2, CN, CF3, Cl, Br) bound to coordinated pyridylimine ligands has been studied for the effect on spin crossover in their Fe(II) complexes. Variable-temperature UV-visible spectroscopic studies performed on complexes with more strongly electronegative ligand substituents revealed spin crossover (SCO) in the solution, and thermodynamic parameters associated with the spin crossover were estimated.

A Known Iron(II) Complex in Different Nanosized Particles: Variable-Temperature Raman Study of Its Spin-Crossover Behavior

2019 ◽  
Vol 58 (8) ◽  
pp. 5183-5195 ◽  
Author(s):  
Zoi G. Lada ◽  
Konstantinos S. Andrikopoulos ◽  
Athanassios Chrissanthopoulos ◽  
Spyros P. Perlepes ◽  
George A. Voyiatzis
Keyword(s):  
Spin Crossover ◽  
Variable Temperature ◽  
Nanosized Particles ◽  
Crossover Behavior ◽  
Raman Study

A large dinuclear Fe(ii) triple helicate demonstrating a two-step spin crossover

2020 ◽  
Vol 56 (62) ◽  
pp. 8838-8841
Author(s):  
Kyle J. Howard-Smith ◽  
Alexander R. Craze ◽  
Hikaru Zenno ◽  
Junya Yagyu ◽  
Shinya Hayami ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Spin Transition ◽  
Triple Helicate

The largest reported dinuclear Fe(ii) triple helicate system to exhibit spin crossover is presented, with exploration of the two-step spin-transition.

scholarly journals Spin-Crossover in Iron(II) Complexes of N,N′-Disubstituted 2,6-Bis(Pyrazol-3-yl)Pyridines: An Effect of a Distal Substituent in the 2,6-Dibromophenyl Group

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 922
Author(s):  
Igor A. Nikovskiy ◽  
Alexander V. Polezhaev ◽  
Valentin V. Novikov ◽  
Dmitry Yu. Aleshin ◽  
Rinat R. Aysin ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Spin Crossover ◽  
Molecular Design ◽  
Variable Temperature ◽  
Bromine Atom ◽  
X Ray Diffraction ◽  
Methyl Group ◽  
X Ray ◽  
Active Iron ◽  
Switchable Materials

A series of new bis(pyrazol-3-yl)pyridines (LR) N,N′-disubstituted by 4-functionalized 2,6-dibromophenyl groups have been synthesized to study the effect of a distal substituent on the spin-crossover (SCO) behaviour of the iron(II) complexes [Fe(LR)2](ClO4)2 by variable-temperature magnetometry, NMR spectroscopy, and X-ray diffraction. The SCO-assisting tendency of the substituents with different electronic and steric properties (i.e., the bromine atom and the methyl group) in the para-position of the 2,6-dibromophenyl group is discussed. Together with earlier reported SCO-active iron(II) complexes with N,N′-disubstituted bis(pyrazol-3-yl)pyridines, these new complexes open the way for this family of SCO compounds to emerge as an effective ‘tool’ in revealing structure–function relations, a prerequisite for successful molecular design of switchable materials for future breakthrough applications in sensing, switching, and memory devices.

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